From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 83FF0C43466 for ; Mon, 21 Sep 2020 15:40:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1B44C20888 for ; Mon, 21 Sep 2020 15:40:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727302AbgIUPkG (ORCPT ); Mon, 21 Sep 2020 11:40:06 -0400 Received: from foss.arm.com ([217.140.110.172]:45594 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726690AbgIUPkF (ORCPT ); Mon, 21 Sep 2020 11:40:05 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 38657147A; Mon, 21 Sep 2020 08:40:05 -0700 (PDT) Received: from [192.168.0.110] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 305293F718; Mon, 21 Sep 2020 08:40:04 -0700 (PDT) Subject: Re: [PATCH v6 0/7] arm_pmu: Use NMI for perf interrupt To: Will Deacon Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, mark.rutland@arm.com, maz@kernel.org, catalin.marinas@arm.com, swboyd@chromium.org, sumit.garg@linaro.org References: <20200819133419.526889-1-alexandru.elisei@arm.com> <20200921135951.GN2139@willie-the-truck> From: Alexandru Elisei Message-ID: <296304b8-aadd-817d-bb12-dc7524b6f0f5@arm.com> Date: Mon, 21 Sep 2020 16:41:00 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20200921135951.GN2139@willie-the-truck> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Will, Thank you so much for reviewing the series! On 9/21/20 2:59 PM, Will Deacon wrote: > On Wed, Aug 19, 2020 at 02:34:12PM +0100, Alexandru Elisei wrote: >> The series makes the arm_pmu driver use NMIs for the perf interrupt when >> NMIs are available on the platform (currently, only arm64 + GICv3). To make >> it easier to play with the patches, I've pushed a branch at [1]: > This mostly looks good to me, but see some of the comments I left on the > code. One other thing I'm not sure about is whether or not we should tell > userspace that we're using an NMI for the sampling. Do any other > architectures have a conditional NMI? I'm not sure about other architectures being able to configure the perf interrupt as NMI or a regular interrupt, I'll try to find out. Regardless of what the other architecture do, I am of the opinion that we should spell out explicitly when the PMU is using pseudo-NMIs, because it makes a huge difference in the accuracy of the instrumentation and the overall usefulness of perf. If I spin a v7 quickly, is it still time to merge the series for 5.10? Thanks, Alex